Method of refining an enzymatically produced fructose containing soultion

ABSTRACT

AN ENZYMATICALLY PRODUCED FRUCTOSE-CONTAINING SOLUTION IS REFINED BY SEQUENTIALLY TREATING THE SOLUTION WITH ACTIVATED CARBON, MAINTAINING THE SOLUTION AT AN ACIDIC PH AND CONTACTING THE SOLUTION WITH A STRONG ACID CATION EXCHANGE RESIN IN THE HYDROGEN FORM AND THEN WITH A WEAK BASE ANION EXCHANGE RESIN IN THE FREE BASE FORM.

3,834,940 Patented Sept. 10, 1974 v 3 834 940 METHOD OF REFINI NG AN ENZYMATICALLY PRODUCED FRUCTOSE CONTAINING SOULTION Khaja Khaleeluddin and Robert Fredric Sutthofi, Clinton,

' and William Junior Nelson, Camanche, Iowa, assignors to Standard Brands Incorporated, New York, NY.

110,748, now abandoned. Divided and this application Oct. 30, 1972, Ser. No. 302,142

. Int. Cl. C13d 3/14; C13k 1/00, 9/00 US. Cl. 127-46 A Claims ABSTRACT OF THE DISCLOSURE An enzymatically produced fructose-containing solution is refined by sequentially treating the solution with activated carbon, maintaining the solution at an acidic pH and contacting the solution with a strong acid cation exchange resin in the hydrogen form and then with a weak base anion exchange resin in the free base form.

This application is a divisional of copending application Ser. No. 110,748, filed Ian. 28, 1971, now abandoned.

THE INVENTION -will isomerize glucose to fructose. Also, British Pat.

1,103,394 and Japanese 7428 (1966) to Takasaki et al. disclose that microorganisms classified as belonging to the Streptomyces genus, such as Streptomyces flavovirens,

,Streptomyces achromogenes, Streptomyces echinatus and Streptomyces albus produce glucose isomerase. There are many other microorganisms which are disclosed in the art as producing glucose isomerase. A few of the other microorganisms disclosed are, for instance, Aerobacter cloacae, Bacillus megaterium, Acetobacter suboxydans, Acetobacter melanogenus, Acetobacter roseus, Acetoba'cter oxydans, Bacillus fructose and Lactobacillus fermenti.

There are many variables to be considered in the use of glucose isomerase on a commercial scale. For instance, the conditions at which the isomerization reaction is performed affect both the life of the enzyme and the amount of fructose produced. The conditions of isomerization on a commercial scale, generally, are not those which provide maximum life of the enzyme. Glucose isomerase, like all enzymes, is heat sensitive, and as the temperature is increased there is accordingly a decrease in activity of the isomerase due to heat denaturation thereof. At low temperatures, however, the isomerization reaction proceeds so slowlyas to make the process uneconomical. Another factor which must be considered is the pH of the isomerization medium. This affects the life of the isomerase, the amount of psicose formed during the isomerization reaction, and the color and color stability of the isomerized liquor. All these factors must be balanced in order to provide an economical and commercially feasible process. In US. Patent Applications Ser. No. 88,190 and Ser. No. 88,187, now abandoned, both filed 1 No Drawing. Original application Jan. 28, 1971, Ser. No. l

Nov. 9, 1970, incorporated herein by reference, there are disclosed processes designed for commercial utilization. Practicing these processes results in an enzymatically produced fructose-containing solution which has minimal quantities of unwanted by-products, color bodies and color-forming bodies. For instance, the color formed during the isomerization reaction Will preferably be less than 0.05 color units and the fructose-containing solution is exceedingly stable as to color formation during storage. Also, other unwanted by-products, such as psicose, produced during the isomerization reaction are negligible.

Although, as shown above, the enzymatically produced fructose-containing solutions produced by the methods disclosed in the two aforementioned patent applications are relatively pure, it is necessary to refine the same inv order to remove color, color-forming bodies and salts therefrom.

There are many processes known in the art for refining sugar syrups. For instance, in US. Pat. No. 3,305,395 and US. Pats. 3,285,776 and 3,383,245 there are disclosed techniques for refining alkaline isomerized liquors. One of the problems associated with these techniques is that due to relatively high pH values employed during refining unwanted by-products such as psicose are produced.

Therefore, it is a principal object of the present invention to produce a refined enzymatically produced fructose-containing solution that contains substantially no color or psicose and is exceedingly stable as to color formation on storage.

This object and other objects of the present invention, which will be apparent from the following description, are attained in accordance with the present invention by treating an enzymatically produced fructose-containing solution which contains color and color-forming bodies with carbon to remove substantially the major portion of the color and color-forming bodies therefrom, maintaining the solution at an acidic pH, treating the solution with a strong acid cation exchange resin in the hydrogen form and a weak base anion exchange resin in the free base form to remove substantially all the remaining color and color-forming bodies thereby producing a fructosecontaining solution which is bland, substantially colorless and is stable as to color formation on storage and contains substantially no psicose.

The term Color Units used herein is defined by the following:

COLOR UN ITS Color was determined spectrophotometrically by measuring the absorbance of an appropriately diluted liquor in a 1-cm. cell at 450 Ill,u. and 600 m versus water as a reference. The spectrophotometer was a Beckman D K- 2A, manufactured by Beckman Instrument Company. The color was calculated by using the following formula:

A =absorbance at 450 my. A =absorbance at 600 m C=concentration (g./ 100 ml.)

Generally the isomerization reaction is performed at temperatures in the range of 50 to C. and at pH values in the range of 6 to 8.5. In some instances, .there may be present metallic ions to stabilize and/or activate the glucose isomerase. Metallic ions which have been used for this purpose are, for example, the salts of cobalt, magnesium, etc. These pH and temperature ranges are conductive to the formation of color, color-forming bodies and psicose.

below, are produced. Although the present process is H aptly suited for refining fructose-containing solutions produced' by the processes disclosed in the afore-mentioned -patent 'applications; it is also "suitable for refining any "enzymatically produced fructose-containingsolution having the characteristics set forth in Table I.

" TABLE I.-CHARACTERIS'IICS OF UNItEFINED FRUCTOSE-CONTAINING SOLUTIONS [Percent dry basis] 'f bodies. Suitable strong acid cation "Next, the'fructosewontaini'ng solution"i'streatednvitli a strong acid cation exchange resin in the hydrogen form. This treatment removes substantially all the metallic ions which are present during the isomerization reaction. If

, these metallic ions are not removed the ash contentof the solution=will be exceedingly high. A156, this' as; 1 entiremo vesa portion ofthe remaining color and'color forrfning flange-Irwin s, are those marketed'by Diamond ShamroclgCo nderthe trade names: of -Duolit,e,C-3 and DuoliteC 5; .Rohmmnd i-HaasC o hunder the trade nam'e of-Ambcrlite ZO'Oand Dow Chemical Co. under the trade name; of Dowex 50 W.

After treating the solution with -a;strongacid cation p saccharides l Psicose 3 Ranges Glucose Fructose 1 Ash 3 Color units 1 e Typieal to 60 1O to54 Oto 50 Oto 1 0.1 to 0.5-.-. Oto 2.0.

Preferred do 0 to 30".. 0 to 0.5.- 0.1 to 0.2 0 to 0.05. v Most preferred do .-d0 do 0 to 0.1 0.005 to 0.1 0 to 0.03. i I

i 1 Amount of the saccharides principally dependent upon characteristics desired in the product. I 1 n L I B Principally composed of metallic salts which are present during isomerization to stabilize and/or activate the glucose isorncrase.

3 Determined by the method described in the article entitled, Chromatographic Determination of Sac- -charides in Starch Hydrolysates, L. D. Ough (published in Methods of Carbohydrate Chemistry, Vol. IV, page 91 (1964), except that the developing solvent employed was ethyl acetate, pyridm water (8:2 :1 v./v.)

As indicated above, isomerization conditions are conducive to the formation of color, color-forming bodies and psicose. Therefore, the longer the enzymatically pro- I duced fructose-containing solution is held under isomerization conditions subsequent to the isomerization reaction, the greater the amount of impurities formed. Thus, it is advisable to refine the'fructose-containing solutions as soon as possible after the isomerization reaction is completed. If the solution is to be stored for an excessive period prior to refining, the temperature thereof should be lowered to a range of 37 to 60 C. and the pH lowered to a range of from about 4 to about 5.5. This will substantially prevent any further impurity formation in the solution.

In the process of the present invention, the fructosecontaining solution is first refined by a carbon treatment, for instance, by passing the solution through a bed of activated granular carbon or by slurrying the solution. with activated powdered carbon and removing the same by filtration. This carbontreatment will remove the major portion of the color and color-forming bodies from the solution. Typically, when using activated granular carbon a burn ratio of from about 0.1 to about 4, and most preferably about 1 is used. Burn ratio is defined as the pounds of granular carbon that must be reactivated per 100 pounds of solids in the solution processed to obtain a solution having a color of less than 0.01 color units.

Examples of suitable activated carbons are those marketed TABLE Ir.'-cHAnAoTERrsTIosoF REFINED FRU'CTOSE-CONTAINING SOLUTIONS" v [Percent dry basis] trade name of Duolite A-6 and Rqhhi andffilaas C0 under the trade name of Amberli te IRA-93 W It is preferred after the last refining treatment to lower the pH of the fructose-containing solution; to avalue in the range of from about 4.0 to about 4.5: Anysuitable acid may be used for this purpose although it is. preferred to use hydrochloric acid. a v

As the exchange capacity of the resins is decreased, their effectiveness decreases until they must'b'e regenerated. There is a range, however, wherealthough th'ey 'are'not completely effective they do 'still have some' exchai'l ge capacity remaining. When the resins are at thi sfs'taget" y are not suitable by themselves tdbomplet'el'y refine an tose-containing solution. However, they may house ti) partially refine the solution and another set of exchange resins i.e., strong acid'exchange and "weakpbase exchange in free base form whose effectiveness vhas-not -.been*sub.- stantially decreased, used thereafter to; completely-refine the solution. When the first set of exchange resins has substantially lost its exchange capacity, it'iSTgEnerated and the second set of resins is subs'tituted 'therefor and another set of fresh resins substituted forfthe la s't set When the resins are used in this mannerm axilnlitn V tion of the resins is accomplished. I l I i It is another embodiment of the'present inyention-to provide a refined fructose-containingsolution having the characteristics shown in Table II below.

Golorv s 1001a. v Ranges Glucose Fructose chandes I Psiccse 3 Ash un'its stability} Typical '30 to an 10 at 54 o to 50 0,to 0 to 0m cm, 0.02 c m 0.1,, .v a Preferred i do do 0 to 3 0 to 0 5 0 to '0.03 0 to 0.01. 0 to 0.02.

Most preferre do 0 to 0 1 0 to 0.01-.-" 0 to 0.005

1 Amount of the saccharides principally dependent upon characteristics desired in the product.

2 Principally composed of metallic salts which are present during isomerization to stabilize and/or activate the glucose isomerase LDett-znnincd by the method described in the article entitled, "Chromatographic Determination of Saccahrides in'Starch; HydrolysatesPL. D. Ough (published in Mcthods 0f Carbohydrate Chemistry; 'Vol. IV, page 91 (1964)), except thatfthe-dev'eloping' solvent employed was ethyl acetate, pyridine, water (812:1 V.[V.). v l 5:1. I" 1: 4 Color stability is measured by adjustingthe solution to a pH of 4.8, maintaining the solution 1n a balling water bath for one hour and measuring the color developed by the Method F-hi of the Second Edition of the Standard Analytical Methods of the Member Companies of the Corn Industries Research Foundation, Inc.

In a number of uses the refined fructose-containing solution of the present invention provides benefits which could not be achieved by the use of conventional dextrose syrups, invert syrups, sucrose syrups or sucrose. For example, in many applications corn syrups and sucrose are used together to provide a dual sweetening system to obtain the particular functional advantage of corn syrup and the sweetening power of the sucrose. Since the fructose-containing solutions of the present invention are generally very sweet and contain a relatively large amount of monosaccharides, including dextrose, such solutions can replace the dual sweetening system. For the user, a single sweetening system, like the fructose-containing solutions of the present invention, is easier to handle and store. This, of course, provides obvious economic benefits. Furthermore, when sucrose is used in many products, inversion takes place which results in the sweetness of the product varying on storage, i.e., sweetness will vary as more sucrose is inverted. This is especially true in products which are acidic or which produce acidic bodies on storage.

In order to more clearly describe the nature of the present invention, a specific example will hereinafter be described. It should be understood, however, that this is done solely by way of example and is intended neither to delineate the scope of the invention nor limit the ambit of the appended claims. In the Example and throughout the specification, percentages refer to percent by weight unless otherwise specified and are based on the dry substance weight of the fructose-containing syrup.

EXAMPLE I This Example illustrates the refining of an enzymatically produced fructose-containing solution to produce a novel fructose-containing solution.

An enzymatically produced fructose-containing solution was made having the following characteristics:

1 Based on the dry substance present in the solution.

2 Based on the method referred to in Table I, footnte (3),

This fructose-containing solution was adjusted to a pH of 4.5, passed through a bed of activated granular carbon (Pittsburgh SGL) and then through a column containing a strong acid cation exchange resin (Duolite C.3). The pH of the solution after this treatment was about 1.3. Then the solution was passed through a column containing a weak base anion exchange resin in the free base form (Duolite A-6) and adjusted to a pH of 4 to 4.5. This refined fructose-containing solution had the following characteristics:

1 Based on the dry substance present in the solution.

2 Based on the method referred to in Table I, footnte (3).

3 Color stability is measured by adjusting the solution to a. pH of 4.8, maintaining the solution in a boiling water bath for one hour and measuring the color developed by the Method F-14 of the Second Edition of the Standard Analytical Methods of the Member Companies of the Corn Industries Research Foundation, Inc.

From the above it is readily seen that refining an enzymatically produced fructose-containing solution by the method of the present invention results in a solution which has essentially no color and is exceedingly stable as to color formation on storage. Furthermore, it should be noted that no psicose was generated during the refining of the solution.

The terms and expressions which have been employed are used as terms of description and not of limitation, and it is not intended in the use of such terms and expressions to exclude any equivalents of the features shown and described or portions thereof, since it is recognized that various modifications are possible within the scope of the invention claimed.

What is claimed is:

1. A method of refining an enzymatically produced fructose-containing solution wherein said solution is pro duced by enzymatically converting glucose to fructose and contains from about 30 to about 60 percent glucose, from about 10 to about 54 percent fructose, up to about 50 percent polysaccharides, up to about 1 percent psicose, color, color forming bodies and salts which contribute to the ash content of the syrup, comprising treating the solution with activated carbon thereby removing the major portion of the color and color forming bodies therefrom, maintaining the solution at an acidic pH, treating the solution with a strong acid cation exchange resin in the hydrogen form and a weak base anion exchange resin in the free base form to remove substantially all the remain ing color, color forming bodies and the major portion of the metallic constituents of the salts which contribute to the ash content of the solution, said treatments being carried out to provide a fructose-containing solution which is substantially colorless and has little tendency to form color on storage and substantially no psicose is formed during the treatments.

2. A method of refining an enzymatically produced fructose-containing solution as defined in Claim 1, wherein the pH of the solution prior to being treated with activated carbon is in the range of from about 3 to about 5.

3. A method of refining an enzymatically produced fructose-containing solution as defined in Claim 2 wherein the solution being refined has a color of up to about 2 color units.

4. A method of refining an enzymatically produced fructose-containing solution as defined in Claim 2 wherein the solution being refined contains up to about 0.5 percent psicose.

References Cited UNITED STATES PATENTS 3,050,444 8/1962 Holstein 3l F 2,753,279 7/1956 Cushing 12746 A 2,845,369 7/1958 Davis 127-46 A 3,305,395 2/1967 Scallet 99-142 X 3,306,752 2/1967 Ueda 99142 3,616,221 10/1971 Takasaki 1953l F MORRIS O. WOLK, Primary Examiner S. MARANTZ, Assistant Examiner US. Cl. X.R.

UNITED STATES PATENT OFFICE- CERTIFICATE OF CORRECTION 0 Patent No. ,8 u, uo Dated September 10, 197A ln fl Khaja Khaleeluddin, Robert F. Sutthof and William J. Nelson It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column '1, line 3 (in the title "Soultion" should read --Solution--.

Column 1, line '71 to column 2, line 1; delete phrase reading "In U. S Patent Applications Ser. No.' 88,190

and Ser. No. 88,187, now abandoned, both filed Nov. 8, 1970, and substitute therefor --In U. S. Patents 3: and 3: 3

Column 2, line 155 delete atent applications" and substitute therefor --patents--.

Column 2, line 7'1; "conductive" should read -'-conducive--.

Column 3, lines t to 5; delete "U. S. Patent Applications 88,190 and 88,187, both filed Nov. 9, 1970" and substitute g therefor --U. 8. Patents 3,788,9 L5 and 3,69 5 31A".

Column 3, line 113 "patent applications" should read --patents--.

Columns 3-4, Table I; under "Color Units", delete periods g following "2.0", "0.05" and "0.03". In the footnotes to Table I, footnote 3), last line; "(8:2:l v./v. should read (8:2:1 V/V Columns 3- 5 Table II; under Color Stability", delete periods following "0.1", "0.02" and "0.01". In the footnotes Q to Table II, footnote (3), first line, "Saccahrides" should read --Saccharides--. Footnote (3), last line "(8:2:l V./V. delete periods.

Patent No. 3, 83 9 .0 Dated September 10, 197A InVentOr(S) Khaja Khaleeluddin, Robert F. Sutthof and William J. Nelson It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Leiumn 3 line 51; "(Duolite 0.3)" should reac (Duolite C-3)--.

Column 5, line -7; "footnte" should read --footnote--.

Column 5, line 675 "footnte" should. read --footnote--.

Column 6; add the following claims:

5. A method of refining an enzymatically produced fructose-containing solution as defined in Claim 1 wherein the treatments are carried out to provide a fructose-containing solution containing up to about 1 percent psicose, a color of up to about 0.02 color units, a color stability of up to about 0.1 and an ash content up to about 0.05 percent.

6. A method of refining an enzymatically produced fructose-containing solution as defined in Claim 5, wherein the treatments are carried out to provide a fructose-containing solution containing up to about 0.5 percent psicose, a color of -up to about 0.01 color units, a color stability of up to about 0.02 and an ash content up to about 0.03 percent.

7. A method of refining an enzymatically produced fructose-containing solution as defined in Claim 6, wherein the treatments are carried out to provide a fructose-containing solution containing up to about 0.1 percent psicose, a color of up to about 0.005 color units, a color stability of up to about 0.01 and an ash content of up to about 0.01 percent.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION p.

Patent 3, 3 9+ Dated September 10, 19%

Inventor(s) Khaja Kna' leeluddirt- Robert F, Sutth-off and.

William J. Nelson It is certified thaterror appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

The follow-ring art not cited by the Examiner was called to the attention of the Patent Office:

i n British Patent 1,103,591 to Agency of industrial bClIlC and Eechnology.

War-drip, 2:). K. Candy industry Combining Confectioner's ioi rnal, reprint cop- (1970).

Signed and Sealed this fourth Day Of November 1975 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner oj'larents and Trademarks 

